Plants grow by absorbing nutrients and water through their roots and producing energy in their leaves by photosynthesis. The energy for plant growth is produced by photosynthesis, in which light energy is the most critical factor.
Plants grown in the open field are simply supplied light energy by the natural light (i.e., sunlight). However, regarding to plants grown in plant factories or indoor environment, artificial light which is similar to the natural light is utilized in order to manage plant growth.
There are a number of ways to implement the artificial light. It is crucial to provide light intensity characteristics of the artificial light which is favorable to plant growth, which is the core technology in plant factories.
Conventionally, 3-band radiation lamps are commonly used for the artificial light. However, the 3-band radiation lamps are disadvantageous in that power consumption is large and life-time is short. Further, the 3-band radiation lamps are unfavorable to plant growth.
In order to overcome these disadvantages, various lighting apparatuses have been developed with incorporating LEDs. They usually incorporate red-chips in order to implement red-series wavelength band which are crucial to plant growth. They may add blue LEDs or white LEDs to these red-chips so as to implement some target wavelength bands.
However, the red-chips are much more expensive and have much larger power consumption than blue-chips, by which the red-chips are disadvantageous from the operational perspective of plant factories. Despite of the disadvantages, the red-chips are usually incorporated for implementing red-series wavelength band.
Therefore, the technology of the present invention is required, in which light intensity by wavelength bands of lighting apparatuses are arranged by applying red-series phosphor, green-series phosphor, yellow-series phosphor and RGY-phosphor to LED blue-chips, by which the production cost of lighting apparatuses for plant factories is reduced and plant growth is enhanced by improving wavelength characteristics of the lighting apparatuses.